SU1357454A1 - Cast iron - Google Patents

Abstract

The invention relates to metallurgy and can be used in the manufacture of hydraulic equipment castings. The purpose of the invention is to increase the fracture toughness and tightness. New cast iron contains carbon, silicon, manganese, chromium, nickel, cerium, one element from the group containing barium, calcium, strontium, copper, magnesium, aluminum nitrides and iron. The addition of copper, magnesium, strontium, nitrogen, and aluminum in the form of aluminum nitrides to the composition of the cast iron provides an increase in the fracture toughness of 1.2-1.3 times and a tightness of 1.2-1.4 times, table 2. (L oo SP 4; SP 4

Description

1135745А

The invention relates to metallurgy

hygiene, in particular to the development of cast iron compositions for hydraulic equipment castings.

The purpose of the invention is to increase the viscosity of fracture and tightness.

The choice of boundary limits for the content of components in the iron is determined by the following.

The additional alloying of pig iron with nickel microlegates, compacts and stabilizes the metal base, reduces the porosity and other casting defects of castings, improves their tightness and mechanical properties of cast iron. When the concentration of nickel is up to 0.606 May, L is its microalloying influence. The effect on the compaction of the matrix is insignificant, and the tightness of castings is insufficient, and with an increase in nickel concentration of more than 0.28 wt.

Magnesium in the amount of 0.05-0.12 May,% modifies, removes gases, whitens and increases the density of the matrix, its homogeneity and the stability of the structure, which contributes to the sealing of the castings for the hydraulic equipment parts. The compaction of the matrix at a concentration of magnesium to 0.05 wt.% Is insufficient, and with an increase in co10

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Nitrides in the amount of 0.08-0.12 May D have a modifying effect, facilitate the formation and growth of graphite inclusions, strengthen and crush the structure, reduce the waste of modifying additives and increase the density of castings and corrosion resistance, crush the structure of graphite eutectic, hydraulic density increases, which increases the operational durability. When the concentration of aluminum nitrides to 0.03 wt.%, Their effect on the density and operational durability is insignificant, and when the concentration of aluminum nitrides is more than 0.12 wt.%, Their coagulation and coarsening of non-metallic inclusions is observed, the number of inclusions located along the boundaries increases. cast grains, which reduces the density, tightness, plastic and other mechanical properties and their stability.

In the pig iron, the concentration of the main components (carbon 2, 7–3.6 May L; manganese 0.4–1.2; silicon 1.0–2.6) is increased, based on the practice of producing high-strength cast irons, without additional heat treatment. The concentration of chromium (0.03-0.12 us.%) Provides an exception - chill in hydraulic equipment castings and higher tightness. The upper limit of the cnc} -: - traction of chromium (0.12 masD) can be re-magnesium with more than 0.12 wt.%, It can be noted for thick-walled castings.

the loss of magnesium is reduced, the casting properties and the fracture toughness of cast iron in castings are reduced.

The introduction of a metal selected from the group containing strontium, barium and calcium in an amount of 0.01-0.08 wt.% Has a graphitizing effect on the structure of the cast metal, contributes to the spheroidization of graphite and nonmetallic inclusions, reduces gas holding, modifies and crushes the matrix, increases the fracture toughness and plastic properties. The content of modifying components, including the resistance of hydraulic equipment parts. including cerium and metals from the group. The lower limit of the concentration of IU, CC containing strontium, barium and calcium (0.05 wt.%) Is taken from the content of 5

, determined experimentally. The lower limits of their concentration provide a significant increase in the dispersion and tightness of cast iron, while increasing the concentration of more upper limits reduces the fracture viscosity and plastic properties,

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Nitrides in the amount of 0.08-0.12 May D have a modifying effect, facilitate the formation and growth of graphite inclusions, strengthen and crush the structure, reduce the waste of modifying additives and increase the density of castings and corrosion resistance, crush the structure of graphite eutectic, hydraulic density increases, which increases the operational durability. When the concentration of aluminum nitrides to 0.03 wt.%, Their effect on the density and operational durability is insignificant, and when the concentration of aluminum nitrides is more than 0.12 wt.%, Their coagulation and coarsening of non-metallic inclusions is observed, the number of inclusions located along the boundaries increases. cast grains, which reduces the density, tightness, plastic and other mechanical properties and their stability.

In the pig iron, the concentration of the main components (carbon 2, 7–3.6 May L; manganese 0.4–1.2; silicon 1.0–2.6) is increased, based on the practice of producing high-strength cast irons, without additional heat treatment. The concentration of chromium (0.03-0.12 us.%) Provides an exception - chill in hydraulic equipment castings and higher tightness. The upper limit of the cnc} -: - traction of chromium (0.12 masD) can be recommended for thick-walled castings.

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a — at a higher concentration of chromium (more than 0.12 wt.%), casting properties and fracture toughness are reduced.

Copper in an amount of 0.05 to 0.35 wt.% Crushes the structure, microlegates the metallic ocHOEiy, helps to increase the density of castings, harden the solid solution and increase the fracture toughness, fatigue limit and resistance to intercrystalline corrosion, that provides increased operational

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Pr.i, which began with its influence on the structure of the matrix, the strength of cast iron in the castings and the tightness. With an increase in the copper concentration of more than 0.35 wt.%, An increase in the liquation, a decrease in the toughness and stability of the hydrodensity and the structure of the iron in castings is noted.

Phosphorus in the amount of 0.02-0.09 May. micro-matrixes, evenly distributed over the cross section of the castings, changes the nature of the solid solution, reduces the porosity of the castings, increases the stability of the structure, increases the fluidity, increases the dispersion and microhardness of the metal - i ecKoft base, which provides increased tightness. When the phosphorus content is up to 0.02 wt.%, Its effect on the casting properties and leaktightness is insufficient, and when the phosphorus concentration is more than 0.09 wt. it begins to precipitate as a solid mesh along the grain boundaries, reducing the stability of the metal base and the mechanical properties that appear in crack castings.

Sulfur is a harmful impurity in cast iron, which reduces the viscosity of corrosion and density of castings, and it is excluded from the composition of the proposed cast iron.

Melting of cast irons is carried out in coke-gas cupolas with overheating of the metal to 1450-1470 ° C and fine-tuning of the chemical composition in induction mixers. Limestone and soda ash is used for the desulfurization of cast iron. Copper Ml and M2, nickel Hi and H2, alloys AMCH and MM2 h, ferromanganese, ferrocerium and ferrosilicon are used as alloying and modifying additives. The spheroidizing modification is carried out in the chambers with magnesium, and for the secondary modification, ferrosilicon and silicostrontium, nitrided AMSH alloy, and silicon bribery are used. silicocalcium injected into bottling buckets. The absorption coefficients of the components in the iron are,%: Nickel 86-89; magnesium 43-50; aluminum nitride 78-86; calcium 70 - 78; strontium 66-77; barium 67-73 Casting iron into casting molds to produce castings of hydropanels, distributor cases and technological

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Samples were taken at 1400-1410 ° C. The casting of cast iron into casting molds is performed by crane open buckets within 3–15 min after graphitization is added, and their additives are added.

Table 1 shows the chemical compositions of known and proposed cast iron; Table 2 shows the tightness, fracture toughness and other mechanical properties of cast iron.

As can be seen from Table 2, the proposed cast iron provides an increase in fracture toughness (1.2-1.3 times) and tightness of castings (1.2-1.4 times) compared to base iron and can be recommended for body parts of hydraulic equipment, working in conditions of hydraulic pressure,

Claims (1)

Formula inventions and Cast iron containing carbon, silicon, manganese, chromium, nickel, aluminum, nitrogen, cerium, one element from the group containing barium, calcium and iron, characterized in that, in order to increase the fracture toughness and tightness, it additionally contains copper , magnesium, the group additionally contains strontium, and aluminum and nitrogen are contained in the form of aluminum nitrides in the following ratio of components, May,%: 0 five 0 Carbon Silicon Manganese Chrome Nickel Cerium One element from the group - containing barium, calcium and strontium Copper Magnesium Aluminum nitride Iron 2.7-3.6 1.0-2.6 0.4-1.2 0.03-0.12 0.06-0.28 0,003-0,05 0.01-0.08 0.05-0.35 0.05-0.12 0.03-0.12 Else t a and l and c fl t 515 615 660 720 600 645/10 610 720 505 5) 0 570 280 440 510 520 430 300 510 43.5 515 270 275 380